Well off, thanks to a good hand (5)

I believe the answer is:

flush

I'm a little stuck... Click here to teach me more about this clue!

'hand' is the definition.
(poker)

I don't understand how the rest of the clue works.

(Other definitions for flush that I've seen before include "Cleanse by running water" , "Rich" , "colour" , "Look ashamed < , maybe even promising hand" , "Redden; level" .)

Want a hint initially instead of a full solution? Install my app